Image forming apparatus and method for double-sided printing

Abstract

An image forming apparatus and a method are provided. The apparatus includes an image forming unit that discharges ink; a transfer unit that performs a first conveying operation of conveying the sheet in a state in which a first surface thereof faces the image forming unit, and a second conveying operation of conveying the sheet in a state in which a second surface thereof faces the image forming unit after the first conveying operation; a detecting unit that detects a jam of the sheet subjected to the second conveying operation; a setting unit that sets a dry time for drying the ink; and a control unit that controls the transfer unit to start the second conveying operation after the dry time has elapsed after the first conveying operation, wherein the setting unit sets the dry time for a current sheet based on the detection result of a previous sheet.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 an image forming unit configured to discharge ink onto a sheet to form an image on the sheet; 
 a transfer unit configured to perform a first conveying operation of conveying the sheet in a state in which a first surface thereof faces the image forming unit, and a second conveying operation of conveying the sheet in a state in which a second surface thereof faces the image forming unit after the first conveying operation; 
 a detecting unit configured to detect whether a jam of the sheet subjected to the second conveying operation occurred; 
 a setting unit configured to set a dry time for drying the ink discharged onto the first surface of the sheet, and wherein the setting unit sets the dry time for a current sheet; 
 a control unit configured to control the transfer unit to start the second conveying operation after the dry time has elapsed after the first conveying operation; 
 an acquiring unit configured to acquire, as an acquired amount of ink, an amount of ink discharged from the image forming unit onto the first surface of the sheet; 
 a storage unit configured to store a plurality of default times and a plurality of amounts of ink, each of the default times being associated with one of the amounts of ink, and one of the amounts of ink corresponding to the acquired amount of ink, 
 wherein the control unit controls the storage unit to further store:
 a plurality of shortest times, each of which is associated with one of the amounts of ink, 
 a plurality of limit times, each of which is associated with one of the amounts of ink, 
 a previous dry time, which is a dry time for drying the ink discharged onto the first surface of a previous sheet, 
 a previous ink amount, which is an amount of ink discharged to the first surface of the previous sheet, 
 a jam detection result, which is a result of the detecting unit detecting whether the jam occurred in the previous sheet, and 
 a provisional dry time, which is a dry time based on the previous dry time and the jam detection result, 
 
 wherein the control unit is further configured to determine whether one of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, 
 wherein, when the control unit determines that one of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, the setting unit sets said one of the limit times as the dry time for the current sheet, 
 wherein, when the control unit determines that none of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink and the previous dry time is not stored in the storage unit, the setting unit sets the one of the default times that is associated with the one of the amounts of ink that corresponds to the acquired amount of ink as the dry time for the current sheet, 
 wherein, when the control unit determines that none of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink and the previous dry time is stored in the storage unit, the control unit determines whether the detecting unit detects the jam of the previous sheet according to the jam detection result, 
 wherein, when the control unit determines according to the jam detection result that the jam did not occur in the previous sheet, the control unit sets the provisional dry time to be less than the previous dry time, 
 wherein, when the control unit determines according to the jam detection result that the jam did occur in the previous sheet, the control unit sets the provisional dry time to be greater than the previous dry time, 
 wherein, after the control unit sets the provisional dry time, the control unit determines whether the amount of ink discharged to the first surface of the current sheet is equal to the previous ink amount of the previous sheet, 
 wherein, when the control unit determines that the amount of ink discharged to the first surface of the current sheet is equal to the previous ink amount of the previous sheet, the setting unit sets the dry time for the current sheet to be equal to the provisional dry time, 
 wherein, when the control unit determines that the amount of ink discharged to the first surface of the current sheet is not equal to the previous ink amount of the previous sheet, the control unit determines whether the amount of ink discharged to the first surface of the current sheet is greater than the previous ink amount of the previous sheet, 
 wherein, when the control unit determines that the amount of ink discharged to the first surface of the current sheet is greater than the previous ink amount of the previous sheet, the setting unit sets the dry time for the current sheet to be greater than the provisional dry time, 
 wherein, when the control unit determines that the amount of ink discharged to the first surface of the current sheet is less than the previous ink amount of the previous sheet, the setting unit sets the dry time for the current sheet to be less than the provisional dry time, 
 wherein, when the detecting unit does not detect the jam of the current sheet and the dry time for the current sheet is less than the one of the shortest times that is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, the control unit controls the storage unit to store the dry time for the current sheet as said one of the shortest times, and 
 wherein, when the detecting unit detects the jam of the current sheet and one of the shortest times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, the control unit controls the storage unit to store said one of the shortest times as the one limit time associated with the one of the amounts of ink that corresponds to the acquired amount of ink. 
 
     
     
       2. The image forming apparatus according to  claim 1 ,
 wherein the setting unit sets the dry time for the current sheet on the basis of the detection result detected by the detecting unit and the amount of ink acquired by the acquiring unit. 
 
     
     
       3. The image forming apparatus according to  claim 2 , further comprising:
 a dividing unit that divides the first surface of the sheet into a plurality of areas, 
 wherein the acquiring unit acquires the amount of ink from at least one of the plurality of areas. 
 
     
     
       4. The image forming apparatus according to  claim 3 , wherein the acquiring unit acquires the amount of ink based on an amount of ink used in each of the plurality of areas. 
     
     
       5. The image forming apparatus according to  claim 3 , wherein the acquiring unit acquires the amount of ink from an area adjacent to a first edge portion of the sheet, which passes through a contact point before a second edge portion of the sheet in the second conveying operation. 
     
     
       6. The image forming apparatus according to  claim 4 ,
 wherein the setting unit assigns a weight value to each of the plurality of areas and the acquiring unit acquires the amount of ink based on an amount of ink used in each of the plurality of areas and the weight value assigned to each of the plurality of areas, and 
 wherein the setting unit assigns a greater weight value to an area adjacent to the first edge portion of the sheet, which passes through a contact point before the second edge portion of the sheet in the second conveying operation, than an area adjacent to the second edge portion the sheet. 
 
     
     
       7. The image forming apparatus according to  claim 1 , wherein the dry time is a period of time between the first conveying operation and the second conveying operation, during which the sheet not conveyed. 
     
     
       8. The image forming apparatus according to  claim 7 , wherein the transfer unit changes a conveying direction of the sheet when the second conveying operation begins after the dry time. 
     
     
       9. The image forming apparatus according to  claim 1 , further comprising a sheet feeding tray configured to store the sheet,
 wherein the transfer unit comprises a feed roller configured to feed the sheet from the sheet feed tray, and 
 wherein the sheet is conveyed by the transfer unit in the second conveying operation to pass through a contact point between the sheet feed tray and the feed roller. 
 
     
     
       10. A method comprising:
 conveying a current sheet through a first conveyance path; 
 printing a first image on a first surface of the current sheet; 
 setting a dry time for the current sheet with a setting unit; 
 waiting for the dry time to elapse; 
 conveying the current sheet to a second conveyance path; 
 determining whether at least one of a previous sheet and the current sheet jammed; 
 printing a second image on a second surface of the current sheet; 
 acquiring, as an acquired amount of ink, an amount of ink discharged onto the first surface of the current sheet; 
 storing a plurality of default times and a plurality of amounts of ink in a storage unit, each of the default times being associated with one of the amounts of ink, and one of the amounts of ink corresponding to the acquired amount of ink; 
 controlling the storage unit with a control unit to further store:
 a plurality of shortest times, each of which is associated with one of the amounts of ink, 
 a plurality of limit times, each of which is associated with one of the amounts of ink, and 
 a jam detection result, which is a result of determining whether the current sheet is jammed; 
 
 determining with the control unit whether one of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink; 
 when the control unit determines that one of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, setting with the setting unit said one of the limit times as the dry time for the current sheet; 
 when the control unit determines that none of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink and a previous dry time, which is a dry time for drying the ink discharged onto the first surface of the previous sheet, is not stored in the storage unit, setting with the setting unit the one of the default times that is associated with the one of the amounts of ink that corresponds to the acquired amount of ink as the dry time for the current sheet; 
 when the control unit determines that none of the limit times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink and the previous dry time is stored in the storage unit, the determining with the control unit whether the detecting unit detects the jam of the previous sheet according to the jam detection result; 
 when the control unit determines according to the jam detection result that the jam did not occur in the previous sheet, setting with the control unit a provisional dry time to be less than the previous dry time; 
 when the control unit determines according to the jam detection result that the jam did occur in the previous sheet, setting with the control unit the provisional dry time to be greater than the previous dry time; 
 after the control unit sets the provisional dry time, determining with the control unit whether the amount of ink discharged to the first surface of the current sheet is equal to a previous amount of ink discharged to the first surface of the previous sheet; 
 when the control unit determines that the amount of ink discharged to the first surface of the current sheet is equal to the previous amount of ink discharged to the first surface of the previous sheet, setting with the setting unit the dry time for the current sheet to be equal to the provisional dry time; 
 when the control unit determines that the amount of ink discharged to the first surface of the current sheet is not equal to the previous amount of ink discharged to the first surface of the previous sheet, determining with the control unit whether the amount of ink discharged to the first surface of the current sheet is greater than the previous amount of ink discharged to the first surface of the previous sheet; 
 when the control unit determines that the amount of ink discharged to the first surface of the current sheet is greater than the previous amount of ink discharged to the first surface of the previous sheet, setting with the setting unit the dry time for the current sheet to be greater than the provisional dry time; 
 when the control unit determines that the amount of ink discharged to the first surface of the current sheet is less than the previous amount of ink discharged to the first surface of the previous sheet, setting with the setting unit the dry time for the current sheet to be less than the provisional dry time; 
 when it is determined that the current sheet is not jammed and the dry time for the current sheet is less than the one of the shortest times that is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, controlling the storage unit with the control unit to store the dry time for the current sheet as said on of the shortest times; and 
 when it is determined that the current sheet is jammed and one of the shortest times stored in the storage unit is associated with the one of the amounts of ink that corresponds to the acquired amount of ink, controlling the storage unit with the control unit to store said one of the shortest times as the one the limit time associated with the one of the amounts of ink that corresponds to the acquired amount of ink. 
 
     
     
       11. The method according to  claim 10  further comprising:
 feeding the first sheet from a sheet feed tray to a first conveyance path by a feed roller, 
 wherein the sheet is conveyed in the second conveying path to pass through a contact point between the sheet feed tray and the feed roller.